Application of Surface Modified Electrodes as a Nano-detection Tool in the Qualitative and Quantitative Assesment of Hydroquinone in a Cosmetic Cream
Duke Omondi Orata *
Department of Chemistry, University of Nairobi, P.O.Box 30197-00100, Nairobi, Kenya.
Dorcas Gathoni Ngigi
Department of Chemistry, University of Nairobi, P.O.Box 30197-00100, Nairobi, Kenya.
Vincent Ochieng
Department of Biochemistry, University of Nairobi, P.O.Box 30197-00100, Nairobi, Kenya.
*Author to whom correspondence should be addressed.
Abstract
The results presented confirm that when the surface of the carbon graphite working electrode is modified using the beauty crème the modified electrode displays the electrochemical properties of the immobilized cream.
The oxidation/reduction peak potentials for the hydroquinone in the cosmetic cream occurred at 0.61V/0.21V.
Electrochemical calculation from the oxidative charge for the hydroquinone redox process gave a surface coverage of 1.1 x10-10 mol/cm2 corresponding to an electro-gravimetric weight of 3.57 x10-5 g for hydroquinone in the beauty cream, which corresponds to 0.121 x 10-9 g for hydroquinone in the 12g of the beauty cream.
It was also observed that, the hydroquinone in the beauty cream inhibits the polyaniline electro-degradation process at far positive potentials.
The results also indicate that modification of the carbon-graphite working electrode with bentonite; affect significantly the redox processes associated with hydroquinone in the beauty cream, the oxidation/ reduction peaks occur at 0.58V/0.28V. The effect of the bentonite host matrix is attributed to pre-concentration of electroactive species in the montmorillonite matrix.
The observed changes in the redox profile of the hydroquinone in the beauty cream in sodium chloride supporting electrolyte can be attributed to cationic and anionic effects associated with the sodium cation and the high charge density of the chloride anion.
Keywords: Nano-detection tool, cosmetic cream, top-lemon cream, hydroquinone